An adaptive machining approach based on in-process inspection of interim machining states for large-scaled and thin-walled complex parts

Abstract

During the machining process of large-scaled and thin-walled parts such as aircraft structural parts, the deformation is a relatively common phenomenon which seriously affects the machining quality of the parts and may lead the parts to be scrapped. In this paper, interim machining states of workpiece are considered in addition to final machining states for deformation control so as to improve the machining quality and part correct rate. It is very important for large-scaled and thin-walled parts to consider the interim machining states, as considerable deformation has always occurred in interim machining states. The difficulties of deformation control of interim machining states contain two aspects: (1) how to assess whether interim machining states can satisfy process requirements for further machining and (2) how to adjust the tool paths adaptively for further machining so as to make the final machining states correct. In order to address the above difficulties, an adaptive machining approach based on in-process inspection of interim machining states for large-scaled and thin-walled complex aircraft structural parts is proposed in this paper. The actual interim machining state is obtained based on in-process inspection of machining states during the machining process; the essential idea of this paper is that the final machining state of the workpiece can be guaranteed by adjusting the tool path based on the inspection of interim machining states, which is realized by coordinating the dimensional tolerance and geometrical tolerance. In order to realize the new idea, the criterion for determining whether the interim machining state is suitable or not for further machining and the concept of expected final state are introduced. Eventually, the large-scaled and thin-walled complex aircraft structural parts can be machined adaptively according to process requirements. A typical large-scaled and thin-walled complex aircraft structural part is used as a case to validate the proposed approach. The results show that the dimensional error is 0.10 mm and the profile error is 0.06 mm, which can meet the machining requirement of large-scaled and thin-walled complex parts.